Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
  • Conference on Lasers and Electro-Optics
  • OSA Technical Digest (Optica Publishing Group, 1989),
  • paper CPD31

820 nm Colliding-Pulse Modelocked Dye Laser Pumped by a CW Ti:Sapphire Laser

Not Accessible

Your library or personal account may give you access

Abstract

Passive modelocking of femtosecond dye lasers in a ring geometry has produced routinely the shortest and most stable optical pulses [1]. Extension of this concept to the near-infrared spectral region is desirable for a number of reasons. Synchronously-pumped passive modelocked dye lasers have produced femtosecond pulses in the near-infrared [2,3] and using energy-transfer mixtures passive modelocking has been obtained at a number of wavelengths [4]. Direct CW-pumping of an infrared CPM laser (IRCPM) is reported here, using a newly developed high power Titanium-doped sapphire laser. With 3-5 W of CW pump power now available throughout the near-infrared (700-1000 nm), this concept should find applications in new modelocking dye pairs or color center lasers. Figure 1 shows the relevant spectroscopy. Ti-sapphire is well-matched to all-lines argon emission. In the present case, the laser is tuned to 715 nm with up to 3.5 W available in a TEM00 beam [5]. It is interesting to note that a tunable pump allows injection at precisely the optimum energy, minimizing excess Stokes losses in the gain jet which cause thermal instabilities and resulting in a low pump power requirement. A ring cavity [6] is formed with 6 or 7 mirrors which have single-stack high reflectivity coatings. The dye Rhodamine 800 (Exciton LD-800) is selected for this experiment, because its small Stokes shift and correspondingly long fluorescence lifetime (3.5 ns in EG). The saturable absorber HITC-I which is used here is known to exhibit strong photo-isomer modelocking around 805 nm [3]. At a cavity round trip time of 10-12 ns which is conventionally used for R6G and DODCI [1] a serious problem with multiple pulse train formation and instability is observed even when pumping at 1% above threshold. This is due to the shorter gain lifetime in the infrared, and appears to be very fundamental. At shorter cavity lengths (6 ns round trip), this problem is effectively eliminated, and stable single pulse trains are obtained with a significant margin above the pump threshold, which is about 1.5 W.Passive modelocking of femtosecond dye lasers in a ring geometry has produced routinely the shortest and most stable optical pulses [1]. Extension of this concept to the near-infrared spectral region is desirable for a number of reasons. Synchronously-pumped passive modelocked dye lasers have produced femtosecond pulses in the near-infrared [2,3] and using energy-transfer mixtures passive modelocking has been obtained at a number of wavelengths [4]. Direct CW-pumping of an infrared CPM laser (IRCPM) is reported here, using a newly developed high power Titanium-doped sapphire laser. With 3-5 W of CW pump power now available throughout the near-infrared (700-1000 nm), this concept should find applications in new modelocking dye pairs or color center lasers. Figure 1 shows the relevant spectroscopy. Ti-sapphire is well-matched to all-lines argon emission. In the present case, the laser is tuned to 715 nm with up to 3.5 W available in a TEM00 beam [5]. It is interesting to note that a tunable pump allows injection at precisely the optimum energy, minimizing excess Stokes losses in the gain jet which cause thermal instabilities and resulting in a low pump power requirement. A ring cavity [6] is formed with 6 or 7 mirrors which have single-stack high reflectivity coatings. The dye Rhodamine 800 (Exciton LD-800) is selected for this experiment, because its small Stokes shift and correspondingly long fluorescence lifetime (3.5 ns in EG). The saturable absorber HITC-I which is used here is known to exhibit strong photo-isomer modelocking around 805 nm [3]. At a cavity round trip time of 10-12 ns which is conventionally used for R6G and DODCI [1] a serious problem with multiple pulse train formation and instability is observed even when pumping at 1% above threshold. This is due to the shorter gain lifetime in the infrared, and appears to be very fundamental. At shorter cavity lengths (6 ns round trip), this problem is effectively eliminated, and stable single pulse trains are obtained with a significant margin above the pump threshold, which is about 1.5 W. At higher pump powers, extremely stable double-pulse operation is observed with a separation of 1 ns, corresponding to the separation between the gain and absorber jets. Figure 3 shows a typical realtime autocorrelation trace. Pulses of 100 fs duration are obtained at a wavelength of 820 nm, which is determined by the setting of a 2 micron pellicle in the cavity. This result appears to be dispersion-limited, and the incorporation of dispersion compensation in the cavity should allow significantly shorter pulses to be generated. In the present case, the very short cavity precludes the use of the usual fused-silica Brewster prisms for negative dispersion operation, however high dispersion TeC^ prisms will work.

© 1989 Optical Society of America

PDF Article
More Like This
820 nm Colliding-pulse Modelocked Dye Laser

W.H. Knox and F.A. Beisser
WC6 International Conference on Ultrafast Phenomena (UP) 1990

820-nm colliding pulse mode-locked dye laser

WAYNE H. KNOX and F. A. BEISSER
CFR2 Conference on Lasers and Electro-Optics (CLEO:S&I) 1990

Generation of 36 fs pulses around 775 nm from a colliding pulse passively mode-locked dye laser

P. GEORGES, F. SALIN, G. LE SAUX, and A. BRUN
CPD29 Conference on Lasers and Electro-Optics (CLEO:S&I) 1989

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved